Polymer useful for coating

Abstract

A copolymer containing at least two acrylic copolymers having a specific range of glass transition temperatures is disclosed. The copolymer provides a film having excellent physical properties. The process for forming the copolymer is also disclosed.

Description

The present invention relates to a copolymer. More particularly, the present invention relates to a film-forming copolymer having excellent physical properties and the process for forming the copolymer.It is often necessary to heat and dry a coated film to fully reveal the physical properties of a polymer of conventional technology. Generally, the physical properties, such as a strength and elongation, of the film dried at an elevated temperature are superior to those of the film dried at ambient temperature. A film dried at atmospheric temperature has poorer water resistance and blister resistance, especially after long term exposure under humid conditions than a comparable film dried at an elevated temperature. Furthermore, some conventional polymers show poorer film forming ability at low temperature than a comparable film dried at an elevated temperature and are unusable in certain applications. As used herein, the term "ambient temperature" usually means a temperature above 0.d...

AI Technical Summary

Benefits of technology

As shown in the working examples, measurement of tangent delta by a dynamic visco-elasticity elasticity test of the film obtained from the copolymer of the present invention provides a broad single peak distribution in plot of a tangent delta vs. temperature. On the other hand, a blend composition provides an obvious double peak in said plot. It is considered that the single peak distribution in the tangent delta profile suggests a sequential structure, wherein a number of very small domains of acrylic copolymer portion A exist in a phase of acrylic copolymer portion B. It is further considered that the advantageous effects obtained by the copolymer of the present invention are due to such a special structure of the copolymer.

obtained by the copolymer of the present invention are due to such a special structure of the copolymer.

The monomers which may be used to prepare the acrylic copolymer portions A and B include: alkyl ester of acrylic and methacrylic acid, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, 3,5,5-trimethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, cetyl (meth)acrylate, octadecyl (meth)acrylate, octadecenyl (meth)acrylate and cyclohexyl (meth)acrylate; hydroxyester of acrylic and methacrylic acid, such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate. In the present specification, the term "(meth)acrylate" means acrylate and / or methacrylate.

An acid functional monomer, such as, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid and maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate, maleic anhydride; other vinylmonomer such as acrylamide or substituted acrylamides; sodium vinyl sulfonate; phosphoethyl (meth)acrylate; acrylamido propane sulfonate; diacetone acrylamide; glycidyl methacrylate; acetoacetylethyl methacrylate; acrolein and methacrolein; dicyclopentadienyl methacrylate; dimethyl meta-isopropenyl benzyl isocyanate; isocyanato ethylmethacrylate; styrene or substituted styrenes; butadiene; ethylene; vinyl acetate or other vinyl esters, N-vinyl pyrrolidone; amino monomers, such as, for example, N,N'-dimethylamino and (meth)acrylate may be used. Furthermore, a minor amount of multi-functional unsaturated monomer, such as ethyleneglycol dimethacrylate, diethyleneglycol dimethacrylate, divinyl benzene and trimethylolpropane trimethacrylate may be used.

In the present invention, both acrylic copolymer portions A and B contain the units derived from same hard monomer and same soft monomer. The above means that the acrylic portion A contains the units derived from a hard monomer and a soft monomer and the acrylic portion B also contains the units derived from the same hard monomer and the same soft monomer as those used in the portion A. In the copolymer of the present invention, an amount of the acrylic copolymer portion A is from 5 weight % to 40 weight %, preferably from 10 weight % to 40 weight %, more preferably from 20 weight % to 40 weight % based on a total weight of the portions A and B and an amount of the acrylic copolymer portion B is from 60 weight % to 95 weight %, preferably from 60 weight % to 90 weight %, more preferably from 60 weight % to 80 weight %, based on a total weight of the portions A and B.

The Tg of the hard monomer is preferably from 50.degree. C. to 110.degree. C., more preferably from 60.degree. C. to 110.degree. C., most preferably from 70.degree. C. to 110.degree. C. The Tg of the soft monomer is preferably from -10.degree. C. to -90.degree. C., more preferably from -20.degree. C. to -90.degree. C., most preferably from -30.degree. C. to -90.degree. C.

Problems solved by technology

A film dried at atmospheric temperature has poorer water resistance and blister resistance, especially after long term exposure under humid conditions than a comparable film dried at an elevated temperature.

Furthermore, some conventional polymers show poorer film forming ability at low temperature than a comparable film dried at an elevated temperature and are unusable in certain applications.

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